Refined wheat flour (white flour) is used to produce a wide range of popular bakery and snack products, including breads, bagels, muffins, waffles, pizza crusts, cookies, crackers, bakery mixes, fruit and grain bars, tortillas, brownies, pastries, pie crusts, par-baked bakery products, cakes, quickbreads, sweet rolls, donuts, microwavable snack products, snack chips, and extruded snacks, which traditionally have a uniform, light-colored appearance and smooth (non-gritty) texture. Comparatively, products made with traditional whole-grain wheat flour, tend to have a coarser, dense texture and a darker, less consistent appearance. Refined wheat flour is also used in a number of other applications such as pastas, ready-to-drink beverages, instant beverages, meat extenders, meat (vegetarian) substitutes, nutritional bars, and ready-to-eat cereals, confectioneries, seasoning blends, gravy and sauce mixes, soup mixes, roux, coatings or breadings, cookie dough or other ice cream inclusions, and various other applications.
The wheat kernel consists of three fractions, the endosperm, bran, and germ, which are compositionally and morphologically very different. Thus, products will have different coarseness, textures and color depending on the portion of the wheat kernel being used. Refined wheat flour is formed primarily from the endosperm of the wheat kernel along with small amounts of bran and germ. The endosperm comprises approximately 82% of the wheat kernel. The function of the endosperm is to provide energy for the embryonic plant during germination of the wheat kernel. The endosperm contains approximately 75% starch and 10-14% protein. Compared to the bran and germ, the endosperm contains low amounts of fiber, lipids, vitamins, minerals, pigments and other phytonutrients. This helps give the refined wheat flour its consistent, fine, starchy texture and off-white color compared to whole-grain wheat flour. The bran consists of several cell layers and contains a significant amount of fiber. The bran includes the aleurone layer, which separates the endosperm from the bran layers. The aleurone layer is rich in proteins, vitamins and phytonutrients, such as ferulic acid. The germ is rich in lipids, fiber, vitamins, minerals and phytonutrients, such as flavonoids. Thus, refined wheat flour, which is made primarily of endosperm is mainly starch and has limited amounts of fiber, proteins, lipids, vitamins, minerals and other phytonutrients.
While refined wheat flour offers the texture and color consumers desire, it does not have the nutritional value of whole-grain wheat flour. Many consumers, particularly children, prefer the texture, appearance and flavor of bakery and snack products made with refined wheat flour compared to products made from whole-grain wheat flour. It is estimated that only 0.8-1 of the 6.7 servings of grain-based foods that adult Americans (20 years or older) consume per day is whole-grain.
The importance of increasing whole-grain consumption is reflected in the changes in recommendations set forth by government and health organization expert groups. In the Healthy People 2010 Report (National Academy Press, 1999), it is recommended that individuals two years and older should consume at least six daily servings of grain products with at least three being whole grains. In the 2000 Dietary Guidelines for Americans (Fifth Edition, USDA, USDHHS, Home and Garden Bulletin No. 232), a separate recommendation was added for grains, specifically, that individuals should choose a variety of grains daily, especially whole grains. The USDA is in the process of revising dietary guidelines. The 2005 Report of the Dietary Guidelines Advisory Committee supports the development of dietary guidelines that suggest the population “increase daily intake of fruits and vegetables, whole grains, and nonfat or low-fat milk and milk products.” (2005 Dietary Guidelines Advisory Committee Report—Executive Summary). According to the guidelines, “diets rich in whole grains can reduce the risk of coronary heart disease and type 2 diabetes and help weight control.” The Advisory Committee recommends consuming at least three servings of whole grains per day to reduce the risk of coronary heart disease, type 2 diabetes and help in weight maintenance. The American Heart Association, American Diabetes Association and the American Cancer Society also make specific recommendations regarding increasing the consumption of whole grains.
Whole-grain wheat flour has increased nutritional value compared to refined wheat flour because it includes the entire wheat kernel, including the bran, germ and endosperm, rather than primarily just the endosperm, FIGS. 1 and 2. Thus, whole-grain wheat flour is higher in fiber, protein, lipids, vitamins, minerals, and phytonutrients, including phenolic compounds and phytates, which function as dietary antioxidants, when compared to refined wheat flour.
The use of whole-grain wheat flour in products typically made with refined wheat flour changes the texture and color of the products. Since consumers typically prefer the consistent texture and lighter color of products using refined wheat flour, these effects on product texture and appearance limit the use of traditional whole-grain wheat flour in bakery and snack products. When whole-grain wheat flour is used in bakery and snack products in place of the refined wheat flour, the products typically contain visible bran specks, have a coarser, heavier texture, and a darker color compared to products made with the refined wheat flour.
The differences in texture and color, along with the visible bran specks within the product makes the product less desirable to most consumers. It has been found that in many instances the increased nutritional value of the products using the whole-grain wheat flour does not overcome the consumers desire to have a consistent texture, light colored product which does not include bran specks. Based on the nutritional value of whole-grain wheat flour versus refined wheat flour, including the fact that the whole-grain wheat flour contains more fiber, protein, lipids, vitamins, minerals, and other nutrients and less starch, it would be preferred to use whole-grain wheat flour in a variety of prepared products for consumer consumption.
Compared to whole-grain wheat flour, refined wheat flour is higher in calories and starch, while containing only about a fifth of the dietary fiber found in whole-grain wheat flour and about 7-10% less protein than whole-grain wheat flour, as shown in FIGS. 1 and 2. Recently, health practitioners have been promoting the benefits of whole-grain foods. In particular, it is suggested that people should consume lesser amounts of processed foods containing high amount of starches and sugars in order to have a healthier overall diet.
Refined wheat flour contains high amounts of starch. Further, although enriched refined wheat flour contains thiamin, riboflavin, niacin, folic acid and iron added at or above the levels found in the wheat kernel, it does not include fiber, minerals, lipids, and phytonutrients found in whole-grain wheat flour. The fiber, minerals, lipids and phytonutrients that refined wheat flour does include, are generally present in lesser amounts than that found in whole-grain wheat flour, and their presence is largely due to small amounts of bran and germ that are present in refined wheat flour, FIG. 1.
Currently in the United States, consumption of white bread made from refined wheat flour versus whole wheat bread is about 5 to 1. For every five loaves of white bread consumed, one loaf of whole wheat bread is consumed. Given that popular bakery and snack products made with refined wheat flour are low in fiber and do not have the nutritional benefits of their respective whole-grain counterparts, it is important to develop a whole-grain wheat flour that can be used to replace refined wheat flour in bakery and snack products, yet yield products with a desirable texture and appearance that is acceptable to consumers. Such products would have enhanced nutritional value, including increased fiber and antioxidant contents, while retaining the qualities that appeal to a large segment of the population.
Populations that rely on high fiber diets typically have lower rates of heart disease, hypertension, diabetes, obesity, and cancer. In the United States, individuals typically consume 12-15 grams of fiber per day, which is half or less of the recommended level. The development of food products, which are high in fiber and other nutrients without sacrificing the look and feel of refined wheat flour, is desirable.
It is also desirable to increase the amounts of antioxidants in the diet. It is thought that antioxidants, including flavonoids, may play a role in preventing cancer. Thus, it is recommended that individuals increase consumption of foods such as fruits, vegetables and whole grains that contain antioxidants.
The antioxidant activity of food products can be measured by the ORAC (Oxygen Radical Absorbance Capacity) assay. The ORAC assay measures hydrophilic and hydrophobic antioxidant capacities of a food using fluorescein as the fluorescent probe and 2,2′-azobis(2-amidinoporpane)dihydrochloride as the peroxyl radical generator. Using the ORAC assay, the total antioxidant capacity, including the capacity due to the nutritive (Vitamins A, C, and E) and non-nutritive (flavonoids, phenolic acids, carotenoids and other phytonutrients), in a food product can be readily determined. Antioxidants, such as flavonoids, are thought to assist the body in preventing cancer.
Three sets of terms are typically used to define wheat of the species Triticum aestivum (common wheat). The first is hard or soft, which relates to the hardness of the kernel. The second is red or white, which relates to the presence or absence of red pigments in the outer layers of the wheat kernel. Finally, there are winter or spring wheat varieties that are categorized as such depending on when the wheat is planted. Durum wheat is of the species Triticum durum. Durum wheat is distinctly different from common wheat in that it produces very hard kernels and has yellow pigments throughout the endosperm rather than in the outer layers. It is typically used to produce pasta products, while common wheat is used, for example, in breads, cakes, cookies, and crackers.
Refined wheat flour is that flour prepared by grinding and bolting cleaned wheat other than durum wheat and red durum wheat. The Food and Drug Administration (FDA) requires flour to meet certain particle size standards in order to be included in the category of refined wheat flour. That particle size is described as flour in which not less than 98% passes through a cloth having openings not larger than those of woven wire cloth designated “212 μm (U.S. Wire 70)”. According to the FDA Code of Federal Regulations (CFR), enriched flour is refined wheat flour which contains 2.9 mg of thiamin, 1.8 mg of riboflavin, 24 mg of niacin, 0.7 mg of folic acid and 20 mg of iron added per pound of refined wheat flour. Enriched flour may also contain calcium in the amount of 960 mg per pound of refined wheat flour. In order to meet U.S. FDA guidelines, enriched flour may not contain more than 5% by weight of wheat germ or partly defatted wheat germ.
FDA guidelines for whole wheat flour state that it the whole wheat flour is prepared by grinding cleaned wheat, other than durum wheat and red durum wheat, which once ground has a particle size wherein not less than 90% passes through a 2.36 millimeter (U.S. Wire 8) sieve and not less than 50% passes through an 850 μm (U.S. Wire 20) sieve. In whole wheat flour (whole-grain wheat flour), the proportions of the natural constituents in the wheat other than moisture remain unaltered as compared to the wheat kernels. The entire wheat kernel is used. Products are considered to be 100% whole wheat when the dough is made from whole-grain wheat flour, bromated whole wheat flour, or a combination of these. No refined wheat flour is used in these products. Whole-grain wheat flour is considered healthier than enriched refined flour because it contains the entire spectrum of nutrients that are naturally present in the wheat kernel, FIGS. 1 and 2.
In current milling processes, the endosperm is separated from the bran and the germ in order to make refined flour. Meanwhile, the bran, the germ, and a small amount of the endosperm are collected as the coarse fraction. Using current technology, 85% of the coarse fraction particles are too large to pass through a 149 micron (U.S. wire 100 sieve). The coarse fraction is high in protein, vitamins, minerals, and phytonutrients. The coarse fraction typically includes a high microbial load which may further limit the use in food products. Thus, the coarse fraction is generally considered to be a low value by-product, which tends to be used as animal feed. In some milling processes, a portion of the germ is separated and used in food or as an oil source in dietary supplement and cosmetic applications. Typically, less than 25% of the germ is collected for these uses. Although the bran and the germ make up only about 18% of the wheat kernel by weight, they account for about 75% of the nutritional value of the wheat. The coarse fraction cannot readily be used in bakery and snack food applications due to the large particle size of the coarse fraction. Use of the coarse fraction in such applications is limited due to the effects of the coarse fraction on the product's texture and appearance. Currently, the coarse fraction is used in low levels in certain baking and snack food applications, primarily to give a healthier appearance to the products.
Traditionally, whole-grain wheat flour products are not as finely milled as refined wheat flour products. In order to produce ultrafine whole-grain wheat flour using a traditional milling flowsheet, further processing of the coarse fraction is required. A multiple pass hammermilling system that would include an intermediate method for sifting the ground product is required to reduce the coarse fraction to a particle size equivalent to that of refined wheat flour. The current technology, which would use hammermills to reduce the coarse fraction for production of ultrafine whole-grain wheat flour, has a low capacity and a high energy usage per ton of product.
Attempts have been made to produce ultrafine whole-grain wheat products, however, these attempts generally were not economically feasible and generally not accepted by the industry. The processes relied on reducing millfeed (coarse fraction) particle size using traditional grinding methods such as rollermills, hammermills, and bran slicers, which cannot economically or efficiently reduce the coarse fraction particles to the ultrafine granulation required. The process is currently uneconomical due to the high amount of energy usage and capitalization, which is required to grind the coarse fraction using the rollermills, hammermills and bran slicers. Hammermills, rollermills and bran slicers reduce the particle size of the millfeed, (coarse fraction), by using shear and impact as the primary mode of reduction rather than the more efficient method of particle on particle attrition. This is an inefficient way to grind these portions of the wheat kernel.
A typical whole-grain wheat flourmill does not produce whole-grain wheat flour with a particle size comparable to refined wheat flour. Using current technology, the finest granulation of whole-grain wheat flour that is available in the marketplace has a particle size of only 60% through a U.S. Wire 100 sieve. Thus, whole-grain wheat flour is coarse in appearance and is generally unattractive to consumers who prefer to eat refined wheat products, and is also less functional for the baker.
A mill flowsheet is a map of the milling process. The traditional whole-grain wheat flourmill flowsheet is only capable of producing a few types of granular whole-grain flour products, FIG. 3. As such, traditional whole-grain wheat milling technology is not able to achieve adequate particle size reduction to produce whole-grain wheat flour that has similar baking attributes to refined wheat flour.
What is needed is a way to enhance the nutritional value of popular bakery, snack, and food products by utilizing whole-grain wheat flour, while retaining the baking attributes and the “look and feel” of a typical refined wheat flour, thereby producing more palatable whole-grain wheat products for consumers. The process should produce an ultrafine-milled whole-grain wheat flour using the entire wheat kernel, that will allow food product developers to use a higher percentage of whole-grain wheat flour in their bakery, snack, and food products in order to enhance the finished product's nutritional value. The process should yield an ultrafine-milled whole-grain wheat flour which includes the entire wheat kernel. Thus, the ultrafine-milled whole-grain wheat flour will contain all the nutrients found-in the wheat kernel.
The ultrafine-milled whole-grain wheat flour should be able to replace refined wheat flour in traditional bakery and snack products, such as breads, bagels, muffins, waffles, pizza crusts, cookies, crackers, bakery mixes, fruit and grain bars, tortillas, brownies, pastries, pie crusts, cakes, quickbreads, sweet rolls, donuts, microwavable snack products, snack chips, par-baked bakery products, and extruded snacks in order to enhance the nutritional value of the products that contain the flour. The ultrafine-milled whole grain wheat flour should also replace refined wheat flour in food products such as pastas, ready-to-eat cereals, ready-to-drink beverages, instant beverages, meat extenders, meat (vegetarian) substitutes, nutritional bars, confectionaries, seasoning blends, gravy and sauce mixes, soup mixes, roux, coatings or breadings, cookie dough or other ice cream inclusions, and various other applications. The texture of the bakery products, snack products, and food products made with the ultrafine-milled whole-grain wheat flour should be the same as if refined wheat flour was used. The appearance of such bakery, snack, and food products will be more similar to products made with refined wheat flour.
Additionally an ultrafine-milled coarse fraction, which can be used in baking, snack, and food products to enhance the nutritional value of such products is required. The ultrafine-milled coarse fraction should be able to replace up to 100% of refined or whole-grain wheat flour in a variety of bakery, snack, and food products. It would also be advantageous to have an ultrafine-milled coarse fraction having a lower microbial load and a higher antioxidant capacity for use in baked goods, snack products, and food products.